This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
In underground drilling, a drill bit is used to drill a borehole into subterranean formations. The drill bit is attached to sections of pipe that stretch back to the surface. The attached sections of pipe are called the drill string. The section of the drill string that is located near the bottom of the borehole is called the bottom hole assembly (BHA). The BHA typically includes the drill bit, sensors, batteries, telemetry devices, and other equipment located near the drill bit. A drilling fluid, called mud, is pumped from the surface to the drill bit through the pipe that forms the drill string. The primary functions of the mud are to cool the drill bit and carry drill cuttings away from the bottom of the borehole and up through the annulus between the drill pipe and the borehole.
Because of the high cost of setting up drilling rigs and equipment, it is desirable to be able to explore formations other than those located directly below the drilling rig, without having to move the rig or set up another rig. In off-shore drilling applications, the expense of drilling platforms makes directional drilling even more desirable. Directional drilling refers to the intentional deviation of a wellbore from a vertical path. A driller can drill to an underground target by pointing the drill bit in a desired drilling direction.